MicroRNA-122 ameliorates corneal allograft rejection through the downregulation of its target CPEB1.

Transplant rejection is a major cause of corneal transplantation failure. MicroRNAs (miRNAs) are a family of small RNAs that regulates gene expression in a sequence-specific manner. miRNAs have recently been shown to have important roles in human organ transplantation, but reports of miRNAs directly associated with corneal transplantation rejection remain limited. To investigate the role of miRNAs during corneal allograft rejection, we established a mouse penetrating keratoplasty model and used microarrays to screen for differentially expressed miRNAs. Our results revealed that the expression of miR-122 was significantly decreased in the allogeneic group. Consistent with this result, the expression of cytoplasmic polyadenylation element-binding protein-1 (CPEB1), a direct target of miR-122, was significantly increased. Further analysis demonstrated that miR-122 inhibited inflammatory cytokine-induced apoptosis in corneal keratocytes through the downregulation of its target CPEB1. We also found that increased miR-122 expression significantly reduced the risk of corneal transplantation rejection. Thus, our results indicate that miR-122 is an important miRNA associated with corneal graft rejection and can be used as a therapeutic target for the prevention of immune rejection after keratoplasty.